| American Chestnut | |
|---|---|
| American Chestnut leaves and nuts | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Fagales |
| Family: | Fagaceae |
| Genus: | Castanea |
| Species: | C. dentata |
| Binomial name | |
| Castanea dentata (Marsh.) Borkh. |
|
The American Chestnut (Castanea dentata) is a large, deciduous tree of the beech family native to eastern North America. Before the species was devastated by the chestnut blight, a fungal disease, it was one of the most important forest trees throughout its range. There are now very few mature specimens of the tree within its historical range, although many small sprouts of the former live trees remain. However, there are (at least) hundreds of large (2 to 5 ft diameter) trees outside its historical range, in areas where less virulent (hypovirulent) strains of the pathogen are more common, such as the 600 to 800 large trees in northern lower Michigan.[1][2]
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A rapidly growing deciduous hardwood tree, it reached up to 30–45 meters (100–150 ft) tall and 3 meters (10 ft) in diameter, and ranged from Maine and southern Ontario to Mississippi, and from the Atlantic coast to the Appalachian Mountains and the Ohio Valley. There are several related chestnut species, such as the European Sweet Chestnut, Chinese Chestnut, and Japanese Chestnut, which are distinguishable only with difficulty from the American species. C. dentata can be best identified by the larger and more widely spaced saw-teeth on the edges of its leaves, as indicated by the scientific name dentata, Latin for "toothed". The leaves, which are 14–20 centimeters (5–8 in) long and 7–10 centimeters (3–4 in) broad, also tend to average slightly shorter and broader than those of the Sweet Chestnut. The blight-resistant Chinese Chestnut is now the most commonly planted chestnut species in the U.S. It can be distinguished from the American Chestnut by its hairy twig tips which are in contrast to the hairless twigs of the American Chestnut. The chestnuts are in the beech family along with beech and oak, and are not closely related to the horse-chestnut, which is in the family Sapindaceae.
The American Chestnut is a prolific bearer of nuts, usually with three nuts enclosed in each spiny green burr, and lined in tan velvet. The nuts develop through late summer, the burrs opening and falling to the ground near the first fall frost.
The American Chestnut was a very important tree for wildlife, providing much of the fall mast for species such as White-tailed Deer and Wild Turkey and, formerly, the Passenger Pigeon. Black Bears were also known to eat the nuts to fatten up for the winter.
Once an important hardwood timber tree, the American Chestnut is highly susceptible to chestnut blight, caused by an Asian bark fungus (Cryphonectria parasitica, formerly Endothia parasitica) accidentally introduced into North America on imported Asiatic chestnut trees. The disease was first noticed on American Chestnut trees in what was then the New York Zoological Park, now known as the Bronx Zoo, in 1904 by chief forester Hermann Merkel. While Chinese Chestnuts evolved with the blight and developed a strong resistance, the airborne bark fungus spread 50 miles (80 km) a year and in a few decades girdled and killed up to three billion American Chestnut trees. It is thought that panic logging during the early years of the blight may have unwittingly destroyed trees which had resistance to this disease and thus aggravated the calamity.[3]
New shoots often sprout from the roots when the main stem dies, so the species has not yet become extinct. However, the stump sprouts rarely reach more than 6 meters (20 ft) in height before blight infection returns.
It is estimated that the total number of chestnut trees in eastern North America was over three billion, and that 25 percent of the trees in the Appalachian Mountains were American Chestnut. The number of large surviving American Chestnut trees over 60 centimeters (24 in) in diameter within the tree's former range is probably fewer than 100. Huge planted chestnut trees (featured in National Geographic) can be found in Sherwood, Oregon, since much of western North America is still free of blight. American Chestnut thrives as far north as Revelstoke, British Columbia. Though the tree is rare east of the Mississippi River in modern times, it exists in pockets of the blight-free West, where the habitat was agreeable for planting: settlers brought seeds for American chestnut with them in the 19th century and it is in part because of this fact that the species still exists.
Several organizations are attempting to breed blight-resistant chestnut trees. One of these is the American Chestnut Cooperators Foundation, which breeds surviving all-American chestnuts, which have shown some native resistance to blight. The Canadian Chestnut Council is an organization attempting to reintroduce the trees in Canada, primarily in Ontario. Another is The American Chestnut Foundation, which is backcrossing blight-resistant American Chestnut × Chinese Chestnut hybrids to American parents, to recover the American growth characteristics and genetic makeup, and then finally intercrossing the advanced generations in order to breed consistently for blight resistance. The goal is eventually to reintroduce the species to the eastern forests of North America. In 2005, a hybrid tree with mostly American genes was planted on the lawn of the White House;[4] as of November 2007 reports indicate that this 75% American Chestnut tree is not doing well.[5]
The United States National Arboretum also has taken an interest in the American Chestnut, using similar methods of backcrossing to create hybrids resistant to blight. It is anticipated that the species may be ready for trial plantings in forests by 2010.
A breakthrough in cross-breeding of American chestnut DNA and Chinese chestnut DNA has allowed to begin restoration of the American chestnut tree. A tree planted in 2005 in the tree library outside of the USDA building is still very healthy 7 years later containing 98% American chestnut DNA and 2% Chinese chestnut DNA. This tree contains enough Chinese chestnut DNA to resist the blight which is essential for restoring the American chestnut trees into the Northeast.[6]
The nuts were once an important economic resource in the U.S., being sold on the streets of towns and cities, as they sometimes still are during the Christmas season (usually "roasting on an open fire" so their smell is readily identifiable many blocks away). Chestnuts are edible raw or roasted, though typically preferably roasted. Nuts of the European Sweet Chestnut are now sold instead in many stores. One must peel the brown skin to access the yellowish-white edible portion. The unrelated horse-chestnut's "conkers" are poisonous without extensive preparation.
The wood is straight-grained, strong, and easy to saw and split, and it lacks the radial end grain found on most other hardwoods. The tree was particularly valuable commercially since it grew at a faster rate than oaks. Being rich in tannins, the wood was highly resistant to decay and therefore used for a variety of purposes, including furniture, split-rail fences, shingles, home construction, flooring, piers, plywood, paper pulp, and telephone poles. Tannins were also extracted from the bark for tanning leather. Although larger trees are no longer available for milling, much chestnut wood has been reclaimed from historic barns to be refashioned into furniture and other items. "Wormy" chestnut refers to a defective grade of wood that has insect damage, having been sawn from long-dead blight-killed trees. This "wormy" wood has since become fashionable for its rustic character.
This tree is not considered a particularly good patio shade tree because its droppings are prolific and a considerable nuisance. Catkins in the spring, spiny nut pods in the fall, and leaves in the early winter can all be a problem. These characteristics are more or less common to all shade trees, but perhaps not to the same degree as with the chestnut. The spiny seed pods are a particular nuisance when scattered over an area frequented by people.
Montreal, Quebec, is famous for its abundance of chestnuts in the downtown core during the autumn months. One may find a festival of ripened harvested chestnuts along rue Sherbrooke. Native Montréalers dub it the Le Festival De La Châtaigne, which generally occurs during the last week of September.
